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Heat Exchangers

Keeping heat exchangers clean is an important aspect of routine maintenance. Without regular cleaning, fouling and debris reduce heat exchanger efficiency and can, if left unchecked, cause equipment and processes to fail.

Shutdowns due to heat exchanger failure can cost hundreds of thousands of dollars – many times the cost of performing even the most complex cleaning procedures. When performed correctly, however, heat exchanger cleaning will improve performance and save money.

1. Ultra-High-Pressure Jetting Methods

Remote and multi-lance ultra-high pressure water jetting should be one of the first choices for every heat exchanger cleaning program because it is effective and environmentally friendly. Using nothing but water, it is possible to successfully remove deposits and scale from heat exchangers, tube bundles and surrounding systems.

Using water reduces the need for specialist disposal of potentially harmful solvents and detergents. This also will help to lower the costs of cleaning and maintenance by negating the need for hazardous chemical disposal services.

Finally, depending on the specifics of your heat exchanger, you may find that the materials used in its construction are weakened or destroyed by certain chemicals. For instance, titanium pipework – common in gas liquefaction plants – is vulnerable to damage caused by acidic cleaning solutions and must be cleaned with either water or some form of mechanical method like drilling.

“The temptation to rush a heat exchanger cleaning job using inappropriate chemicals or even the wrong tools can damage delicate pipework,” says Liz Hunt, contracts organizer at Tube Tech. “High pressure water jetting should be your choice of cleaning method in almost every case even if it needs to be used in combination with another technique like drilling. The cost of making the wrong choice could be enormous.”

2. Keep Cleaning on Schedule

Routine maintenance should – as the name implies – be performed according to a schedule. Depending on the specific heat exchanger in question, the correct timing of maintenance routines may be defined by the manufacturer or set by the onsite maintenance team.

Cleaning according to a routine will prevent deposits and sediment from reaching damaging levels that may force a plant shutdown. Combining cleaning with inspection routines also will help ensure equipment is fully operational and meets regulatory standards.

“If your plant does not already have a routine cleaning cycle for heat exchangers, you should try and implement one as soon as possible,” explains Hunt. “In doing so, you will at least be able to extend the period between bare-metal cleans, which are more costly and time consuming.”

3. Clean In Situ

Robotic heat exchanger cleaning techniques now allow for maintenance to be performed without disassembly. This is a good solution for plant operators looking to minimize downtime and associated costs.

Some specialists only undertake cleaning on heat exchanger equipment at their own facility, but the additional downtime incurred by this methodology is unacceptable to most businesses.If your current contractor is unable to clean your heat exchanger in place, do not hesitate to seek a second opinion from another service provider who may have an alternative cleaning method that can complete the job on-site, reducing the time to project completion.

4. Go ‘Bare Metal’

When cleaning heat exchangers, it is important to remove all deposits and sediment, taking pipework back to bare metal. Failure to remove all fouling will not deliver the benefits expected and reduce the return on investment in maintenance.

Choosing to go back to bare metal significantly extends the periods between cleaning cycles by effectively returning pipework and surfaces to factory-new standard. By removing all scale and buildup, plant efficiency will increase as will the return on investment in advanced cleaning services.

Polishing the insides of pipework will help improve liquid throughput by removing many of the microscopic blemishes that become sites for new deposits to begin building from. Ask your service provider to perform a videoscope inspection following completion of cleaning to verify the finish and level of cleaning achieved.

5. Remember External Surfaces

Tube bundles, interior pipework and shell sides often are the highest priority for cleaning because these surfaces are most likely to be affected by chemical deposits and buildups.However, the outer surfaces of heat exchanger equipment also play an important part in heat dissipation and efficient operations.

Cleaning the outer surfaces of heat exchanger equipment also should be included as part of the regular maintenance program, not least because it helps make carrying out visual inspections much easier. Scheduling external cleaning of heat exchangers should be much easier, requiring little, if any, downtime. This also will make it much easier to secure the services of your preferred cleaning contractor because the slightly less urgent nature of the project means you can be more flexible with the start date.

6. Use the Right Tools

Polymer deposits are particularly challenging to remove, with some operators even using hammers, chisels and chainsaws to try and clear buildups. When dealing with precision equipment, using generalized tools like these will almost certainly result in damage to equipment and wasted effort by employees.

“In the past, we have worked with companies whose approach to clearing blockages caused by fouling has been unusual,” says Liz Hunt. “We have not only seen businesses using hammers and chisels to try and remove deposits, but also turbine and pneumatic drilling. Given enough time, these methods may have cleared some of the fouling, but the results would be variable at best.”

In almost every case, plant equipment can be cleaned with a combination of ultra-high-pressure water jetting, bandsaws and patience. The thicker polymer deposits become, the longer they take to clear. This further emphasizes the importance of regular, routine cleaning and maintenance.

7. Never Accept Standard Cleaning Techniques

Many industrial service providers continue to use the same narrow array of cleaning techniques simply because “that’s the way it’s always been done”. Standard cleaning techniques are often quite effective but can fail to account for developments in heat exchanger technology that make the job more complicated.

Worse still, standard cleaning techniques can be slower to use and have variable results, meaning that your heat exchanger may not be cleaned as thoroughly as possible. Traditional water jetting techniques fail to account for shell-side residue, meaning that as much as 50% of deposits are left behind after the cleaning operation has finished. In effect, standard cleaning techniques can only hope to improve heat exchanger performance by half.

Advanced cleaning techniques can remove shell-side deposits from heat exchangers, further underlining the importance of not settling for standard services. By cleaning both sides of the heat exchanger, performance gains will be much higher.

Far better for your heat exchanger – and ultimately your profits – is to liaise with suppliers who create innovative solutions or combine proven techniques for cleaning. Newer techniques may be more effective and complete cleaning projects more quickly and efficiently than standard alternatives.

In conclusion, these seven tips will help your business cut costs and downtime, and they can help ensure your heat exchangers are cleaned to the point that they raise profitability. If you find that your current provider is unable to meet these expectations, consider securing the services of a new one. While researching suppliers, make sure that you obtain evidence of any supplier’s expertise such as customer testimonials. You should also verify that any potential provider of cleaning can further reduce your maintenance costs by combining services such as camera inspection and 3D modelling to perform internal visual inspections in conjunction with cleaning cycles.

Ben Lloyd writes on emerging technologies in thermal processing. For more information from Tube Tech, a provider of high-tech cleaning and inspection services, call +44 (0)1268 786999, send an email to info@tubetech.com or fill out our contact form.

External shell side fouling before cleaning